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What is the value of x?

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What is the value of x?  [#permalink]

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New post 01 Nov 2018, 08:04
1
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

80% (00:47) correct 20% (01:15) wrong based on 58 sessions

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Re: What is the value of x?  [#permalink]

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New post 01 Nov 2018, 08:29
gmatbusters wrote:
What is the value of x?
(1) 2x + 3y = 12
(2) 5x + 7y = 29


We need to find the value of x

(1) 2x + 3y = 12. It represents a straight line and infinite values of x and y satisfy it ( by satisfying the equation) Hence not sufficient!

(2) 5x + 7y = 29 Not sufficient for same reasons as above.

(1) + (2) together : If the two lines intersect in one point we have a unique value of x and y. Let's solve to see if they do ( as we need to eliminate the possibility of two coincident lines)

2x + 3y = 12 ... Multiply by 7
5x + 7y = 29 ... Multiply by 3

14x + 21y = 12*7
15x + 21y = 29*3

Subtract the first one from the second one...

x = 29*3 - 12*7

Hence we can determine a unique value of x.

So Option (C) is our choice.

Best,
Gladi
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Re: What is the value of x?  [#permalink]

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New post 03 Nov 2018, 16:06
1
gmatbusters wrote:
What is the value of x?
(1) 2x + 3y = 12
(2) 5x + 7y = 29


Looks like OA is wrong. It should be C not A. Please correct me if I am wrong.

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Re: What is the value of x?  [#permalink]

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New post 03 Nov 2018, 18:17
Thanks for pointing out the typo.

OA is revised.

dollytaneja51 wrote:
gmatbusters wrote:
What is the value of x?
(1) 2x + 3y = 12
(2) 5x + 7y = 29


Looks like OA is wrong. It should be C not A. Please correct me if I am wrong.

Posted from my mobile device

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Re: What is the value of x?   [#permalink] 03 Nov 2018, 18:17
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